To cut manufacturing costs and provide better purchase deals, ambulance manufacturers usually use a pickup truck that they convert into an ambulance by adding a box over the pickup bed, emergency lights and horns, medical equipment, etc. This conversion is carried out without changing the base structural components of the pickup, like the suspension system which is usually of the spring blade type. With all the medical equipment load and the sever drive conditions, the suspension is put to heavy test, and is subjected to damageable shocks. The ambulance is likely to continuously swing during travel, which is highly uncomfortable for the passengers and the driver. This also causes spring sag and vehicle instability.
Known in the art are U.S. Pat. No. 3,556,554 (Saward); U.S. Pat. No. 3,785,673 (Harbers, Jr. et al.); U.S. Pat. No. 3,909,036 (Pound); U.S. Pat. No. 4,256,326 (Cantrell et al.); U.S. Pat. No. 4,923,210 (Heider et al.); U.S. Pat. No. 5,346,247 (Snyder); U.S. Pat. No. 5,351,986 (Hedenberg et al.); and U.S. Pat. No. 5,362,095 (Eveley), which all disclose various types of air assisted suspensions. In all the cases, the air shock absorber or pneumatic spring, generally in the form of an air bag, is mounted between the suspension arms and the vehicle chassis, thus requiring substantial structural adaptations on the vehicle chassis to accommodate the mounting of the suspension.